The present invention relates to a door lock in which a sliding bolt is reciprocally movable between a closed position and an open position by a linear longitudinal movement of a handle to which the bolt is attached.
There have been provided in the prior art various constructions in which a bolt is slidable by a pivoted handle, and in which the bolt may be selectively locked into the extended or locking position thereof by a key-operated barrel lock.
U.S. Pat. No. 4,168,854 shows a lock assembly in which a bolt is slidable by rotation of a pivoted handle connected to the bolt by a toggle link pin connected to the bolt and handle. The handle is channel-shaped in cross section, and covers the toggle link in the locked position. The handle rotates through 180 degrees to move the bolt between open and closed positions. A key operated barrel lock contained in a housing through which the bolt passes has an exterior groove enclosing a portion of the bolt when the barrel lock is in the open position, and the bolt has a construction which receives the key-operated barrel lock when the bolt is in the closed position to lock the bolt. A flexible pin depends from the bolt, and in the open position engages a stop on the housing plate to stop further withdrawal of the bolt from the housing.
Three disadvantages of such a device are: the bolt is not rotatable axially, thereby permitting sawing of the bolt to break open the locked door; when the lock is in its locked position, the handle can be rotated open by about twenty-five degrees thereby allowing an intruder the opportunity to pry off the lock; and, when the lock is in its open position, the handle extends downwardly an excessive amount, exposing the toggle elements to view, creating an esthetically unpleasant appearance. Additionally, the toggle type configuration inherently produces a more complex locking structure than is provided by a longitudinally slideable handle structure and may be difficult to open when in its closed position due to the necessity of pulling outwardly on the smooth handle to overcome the toggle over-center action.